perhaps you are already familiar w my thread: "Making the case for the <rotary> powered FD: The Fix" (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/making-case-rotary-powered-fd-fix-806104/) should you wish further background after reading this i suggest you check it out.

the stock turbo'd rotary can make 395 rwhp cranked to the max so the turbos can generate as much as 758 CFM or 52 pounds per minute. since that output level puts them in cavitation greatly shortening their life, lets just take a closer look at the 300 rwhp level...

300 = 576 CFM = 40 pounds per minute of air.

at a 11 to 1 AFR...

40 pounds of air

3.636 pounds of fuel (AFR relationship is normally measured in pounds)

converting pounds of gasoline to gallons...

3.636/ 6.35 = .572 gallons per minute to make 300 rotary rwhp (Rrwhp)

gasoline is a fuel and as such has X number of BTUs per unit...

116,090 BTUs per gallon

.572 BTUs X 116,090 = 66,403 BTUs to make 300 Rrwhp

gasoline also has another important characteristic: it's cooling ability. expressed as BTUs... 952 BTUs of COOLING per gallon.

we are using .572 gallons per minute (GPM) so total COOLING is

.572 X 952 = 544 BTUs of cooling per minute to make 300 Rrwhp

turbos make huge amounts of air/oxygen easily possible. with increased airflow comes increased Combustion Chamber Pressure (CCP).

CCP= HEAT= increased knock/preigniton = increased calls to engine builders

but, hey, we are just running the stock turbos and have modest upgrades... in a world where 400/500 rwhp is common our 300 is a conservative tune, right?

uh, no.

300 rw is 345 flywheel hp. 345/ 159 cubic inches is 2.17hp per cubic inch.

Chevrolet stopped the tune of the $100,000+ Supercharged Intercooled Corvette ZR1 at 1.69 hp / cu inch. draw your own conclusions.

'still think you have a conservative tune?

Mazda, knowing the potential for high CCP levels added additional fuel to the motor to gain additional cooling. to keep it simple let's just say 10%.

sure, Mazda knew all about the various AI options but they probably figured, as did Buick, that the general public wouldn't want to go thru the hassle of adding water to a tank.

of course you aren't the "general public."

so, Mazda just added more fuel and with the fuel came lots of carbon, less hp, less MPG and decreased driveability.

you can fix all these things and the numbers are astounding!

i recently did a thread that you might find valuable if you wish more info... "Feeding the Turbo Rotary: Horsepower, Airflow, Fuels" (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/feeding-turbo-rotary-horsepower-airflow-fuels-881992/) which is lengthy and a bit wonkish but came to some astounding calculated conclusions which are the reason for this thread.

300 Rrwhp = .572 GPM of fuel = 544 BTUs of cooling

assume we remove 10% of the fuel which is the excess mazda added...

515 GPM of fuel = 490 BTUs of cooling

we lost 54 BTUs of cooling...

now let's add a small amount of water as coolant using the smallest of jets... a 300 CC/Minute nozzle.

water has 8087 BTUs of cooling per gallon.

300 CC is .07925 gallons

.07925 X 8087 = 641 BTUs per minute of cooling!!!!

we have gained 641 BTUs by adding a paltry 300 CC/Min of water which is more cooling than the entire (544) richened gasoline injectant!

since we no longer need the excess gasoline we can withdraw the 10% of excess fuel, losing only 54 BTUs while adding 641!!

now we have a much lower CCP/cooler engine, better MPG, more power, while we are steam cleaning all the carbon that has accumulated by running too rich!

total cooling from the 90% gas map = 489 BTUs

total cooling from 300 CC of water = 641 BTUs

WOW
if you aren't running water maybe it should be on your list for 2010.

howard coleman

 

On my list.

 

Your post count is too low you cant post here be off with you!!

~S~

 

New business venture eh, Howard?

 

sitting in my garage!
Thanks again for all the facts Howard.

 

Howard,
Simple Question:

Can I "add" water without retuning, IOW, run the "same" only cooler?

I ask because I love the TT's for the track, but I limit my boost to 12 psi for heat/reliability reasons, even though I consistently run 100 octane. One time in the fall I forgot to turn it down from the 15 psi I run on the street, and the car flew. If I could "add" water and run 15 psi with no more downside than I have running 12 psi now, that would be a winner. Car made 343 rwhp @12 and 365 @15 psi, tuned to an 11.4/1 AFR at WOT.

Needing to retune what is currently a great tune by Ray @ PFS is holding me back. Same is true for rewiring my fuel pump or adding a 3-bar map sensor.

 

On my list for sure!
I'll try to post back how the install been when its done

 

As always, great info and really gets one thinking.

One comment though, on your website, I would change the background. The checker board really makes it hard to read and was even slightly annoying. A simple color background..or really anything else, would make it a lot more "friendly".

That's just my opinion though.

Good job

 

Simply Amazing.

Meth/water injection is on my list...


God I love the 3rd gen section..


Thanks for taking the time to write this all out and sharing this with all of us.


-jaime.

 

"Howard,
Simple Question:

Can I "add" water without retuning, IOW, run the "same" only cooler?"

Peter, a simple answer:

yes

 

Now that you've said it maybe goodfella will believe it. I tried to tell him something similar and he refused to believe me.
I read something similar on turbobuicks, but with less maths. Very well said

I am considering running one of aquamists kits this year.

 

Great post. Its on my list for this year Just trying to figure out which kit is "best" for my setup.

Could anyone make a recommendation of what kit to use for a 13b & 500r single @ 15psi?

 

Why is the only argument against conservative HP/displacement alone? Proper tuning, timing, a turbo that's not so far out of it's efficiency that the IAT isn't hot enough to predetonate already, etc are just as large of factors. Then there's the fact that the applied combustion forces are less likely to cause catastrophic failures at lower power. I realize every one of those reasons has been covered already, but they're more relative to arguing for staying conservative than a comparative HP/cu. Saying it's 'necessary' or a 'fix' seems an awful lot like a sales pitch. We all know that you can have a reliable, conservative 300whp car with a proper tune/hardware. Nothing's broken unless you run into either bad gas/pushing the turbo's so far past their limit you're causing temperature rise enough to detonate/or something else fails. It'd make more sense to call it an insurance policy upgrade. It lets you make more power with equipment past it's limit, it saves you from bad gas/tunes, it cleans and cools. Is there some kind of hidden agenda behind theses new threads/bumps? Sure, they have good information, but it's all pretty much a repeat of your original thread. Wouldn't it have just been easier to sticky the original?

And for what it's worth, the reason Chevy probably decided to stop the tune at 1.69 is the same reason Mazda decided to stop the tune of their $50k+ (Inflated) RX7's at 1.60.

Stock 13B-REW - 255bhp - 1.6hp/cu in.
Stock LS9 - 638bhp - 1.69hp/cu in.

 

I just installed an AEM injection kit on my stock car (besides HKS downpipe), stock boost. No tuning, all stock. Running the 315cc/min AEM jet with problems.

 

(I'll post something technical later on)

Blah Blah Blah.......

 

^ should believe it. Because its a fact.

 

I never said I didn't believe it. Mr. Retardo up above did. I've been running water injection for over 4 years now (and been espousing it's virtues for ~9 yrs)

 

with?! I hope that's a typo

 

it's not news, course people have been using this technology for at least 50 years now.

course i won't argue with the benefits though, if it were up to me i would put an AI kit on every car along with premixing fuel as a requirement.

 

"....is there some kind of hidden agenda behind these threads/bumps?..."

You know, if you've followed this forum for the past 5-10 years you would realize that most of the hardcore info on repairing/modding the FD has been covered years ago. Not all the guys providing that info/threads are still here on the forum. For whatever reason.
When a noob asks almost any question there's always an answer directing him to the "search" feature. A lot has been covered already.
I dont know howard coleman personally but his technically in depth threads always draw my attention and teach me something.
AI may not be new, and some may know that it works well, but I'm sure even less know WHY it works well.
So its good, ifryrice, that you questioned some of what howard coleman is doing. It just makes the rest of us appreciate what he is doing on this forum even more. There's not many more on here who are adding to the average forum users knowledge base.

 

I've been here since the wonderful issues of '01 and the massive pissing contest over everyone losing their post counts. (Oh, and i know this SN is low post count/new, my original won't let me stay logged in and just constantly resets every time I change pages.) I'm not knocking, or discrediting the threads in anyway. I've been using AI for about 6 years now. It just seems odd to me that there's so much of an aggressive attempt to get people in on this. I've got nothing against HC, I just think some of the points/repeat threads/etc seemed a little like a sales pitch, where-as if it was more informational some of the comparative results would've been more in-depth. With humor, it had a Billy Mayes kind of feel, like there's no way my life would be complete without the a supply of mighty putty. Nothing bad implied, and I would hope he realizes that. I just figure it'd have been more beneficial to have all he relative information in a single easy source than a few random ones, and it'd be better presented in the original format where it was more data/etc oriented.

 

No problems!!! Damn computer must have left that word out. What an idiot machine.

Been running stock boost with 315cc/min using peak blue wiper fluid for +20 deg. temperatures which I think is about 10% alcohol.

Runs great, no more heat soak sluggishness anymore because of my tiny stock intercooler. Very pleased and the AEM kit was really easy to set up.

 

FWIW I put my water injection system on for this exact reason. I run 350cc-ish of water at 14psi on the stock twins with zero downsides.

 

"it had a Billy Mayes kind of feel"

Hi, Billy Mayes here for AI

me thinks if the Bill-ster ever did a pitch like post one in this thread he wouldn't even be able to swing those classy polyester shirts he sported...

just for the record ifry, i don't sell, nor do i plan to sell AI systems. i have 3200+ commerce free posts on this board and actually became a vendor yesterday. i do one thing and one thing only... build rotary engines.

and yes i have a number of threads/posts on AI. i also started and have done my best to cultivate the AI section which i am happy to say currently has over 400 threads to date. (lots of good nuts and bolts info therein). my sincere apologies if you find a few of my threads repetitive but if you read them carefully you will find new info in each and the club apparently finds them helpful based on the number of reads.

as to the typical moderate hp'd FD getting along fine without AI.... sure, it is possible.

as an rotary lover/builder i disassemble lots of engines. unless they are running AI they are all way to carboned up. many have poorly functioning apex seals due to the carbon. my motor of 4 years, running pumpgas and methanol was so clean i barely had to clean the rotors. an entirely different look.

the point of this specific thread was to show in clear terms (BTUs of cooling) the profound amount of cooling that can be obtained from a simple system at low delivery levels. generally people talk about the cooling conceptually... speaking in terms of BTUs makes the point...

more cooling from 300 CC than the entire gasoline map delivers. i think this makes a substantive point.

not "selling" AI,

howard

 

Cool thread and site, Howard. Although I can see why some people might question the repetitiveness of your posts, each new thread usually contains at least one more tidbit of useful into than the previous one.

Personally I'd rather re-read the old (but mostly pertinent and useful) info in your threads than sift through another "AT>>MT swap questions" thread, another "check out my polished (but otherwise stock) aluminum engine parts" thread, or another "will the stock ECU handle these mods safely?" thread.


Good luck with your Texas Mile effort, too.